William H. Matthaeus is the Unidel Professor of Physics and Astronomy at the University of Delaware and Director of the Delaware NASA Space Grant Consortium and the Delaware NASA EPSCoR program. Professor Matthaeus received his B.A. degree in Physics and Philosophy from the University of Pennsylvania in 1973. He received a Ph.D. from William and Mary in 1979. His major research interests include the characterization of interplanetary plasma turbulence, the identification of nonlinear dynamical processes in the solar wind using data from spacecraft observations, and the study of coronal phenomena. He has developed new analytical, computational, and observational methods to study the transport of turbulence, the turbulence cascade, and the kinetic plasma physics associated with dissipation and heating in space plasmas. He is a recipient of the James B. Macelwane Award from the American Geophysical Union and the University of Delaware College of Arts and Sciences Scholarship Award. He is a Fellow of the American Physical Society, the Institute of Physics, and the American Geophysical Union. Matthaeus has served as a co-investigator on several spacecraft missions, including Cluster/PEACE, the Magnetospheric Multiscale mission, the Parker Solar Probe ISOIS instruments, and the Interstellar Mapping and Acceleration Probe. For the past decade, he has also been the lead organizer of the Arcetri Workshop on Plasma Astrophysics, hosted by the University of Florence, Italy.
The citation for the 2019 James Clerk Maxwell Prize for Plasma Physics reads
“For pioneering research into the nature of turbulence in space and astrophysical plasmas, which has led to major advances in understanding particle transport, dissipation of turbulent energy, and magnetic reconnection.”
Professor William Matthaeus's fascination in space science began at an early age and grew into a lifelong pursuit beginning with his doctoral dissertation Nonlinear Evolution of the Magnetohydrodynamic Sheet Pinch1 completed under the supervision of David Campbell Montgomery at William and Mary. After graduation, Matthaeus conducted postdoctoral work with Melvyn Goldstein at the NASA Goddard Space Flight Center where he invented a technique to measure magnetic helicity from the two-point correlation of the magnetic field, made the first measurement of the solar wind's magnetic helicity using data from the Voyager 2 spacecraft,2 and demonstrated how to measure the three invariants of magnetohydrodynamic turbulence, total energy, cross helicity, and magnetic helicity, in the solar wind.3 While at Goddard, he launched a series of studies to characterize solar wind turbulence. These included the study of the physics of dynamic alignment and large amplitude Alfvén waves in the solar wind4 and the development of anisotropic magnetohydrodynamic turbulence in the presence of an externally imposed guide field.5
Since joining the faculty at the University of Delaware in 1983, Professor William Matthaeus's many contributions to plasma physics and hydrodynamics have defined the field of plasma turbulence in space. Early achievements include the study of the effects of turbulence on particle acceleration,6 magnetic reconnection,7 and turbulent relaxation.8 Well-known later works from the 1990s include inventing a novel lattice-Boltzmann method for hydrodynamic simulations9,10 and establishing a solid theoretical foundation for reduced MHD.11 First in 1995 and then again in 2004, Matthaeus and co-authors prepared influential reviews explaining how direct spacecraft observations, numerical simulations, and various models lead to understanding of the in situ dynamical evolution solar wind turbulence12 and the fundamental aspects of MHD turbulence, including spectral energy transfer, nonlocality, and anisotropy.13 In 2015, Matthaeus and co-authors reviewed spatial and temporal intermittency in solar wind plasma and showed how earlier studies of intermittency in hydrodynamic turbulence can be extended to the new realm of intermittency in kinetic plasma and the influence of intermittency on dissipation, heating, the transport of charged particles, and relaxation processes, leading to regions bounded by sharp discontinuities, such as current sheets.14
In addition to his research achievements, Professor William Matthaeus served the plasma physics and space physics communities in many capacities. He was a member of the 2003 NAS Decadal Research Strategy in Solar and Space Physics Decadal study15 and served as a member of NASA's Sun-Earth Connections Advisory and Heliospheric Advisory Committees. As the Director of NASA's Delaware Space Grant, he supports educators, students, and researchers in the STEM fields and promotes interest in space research and scholarship. Matthaeus served as a member of the 2000 Program Committee for the APS Division of Plasma Physics Annual Meeting and co-hosted the 2008 APS-DPP Mini-Conference on “Plasma Physics of the Solar Wind: From Parker (1958) to the Present.” As the lead organizer of the Arcetri Workshop on Plasma Astrophysics, Matthaeus has facilitated international work in theoretical topics in the dynamics of solar and heliospheric plasma, and in 2018, he received the Ruth Gall Award for Contributions to Latin American Science.
The title of Professor Matthaeus's Maxwell Prize address was titled “Who needs turbulence? A tour of turbulence effects and outstanding questions in space plasmas.” Matthaeus spoke of widespread effects of turbulence in space and astrophysical plasma and reviewed the status of turbulence physics derived from space-craft observations and remote sensing data and also what has been learned so far from simulations and theory.
